GoodSoundClub - Romy the Cat's Audio Site

In the Forum: Horn-Loaded Speakers
In the Thread: Macondo’s lowest channel.

Post Subject: The crisis of perception.Posted by Romy the Cat on: 11/16/2010

I pretty much know what I need to do – I need to go for shaper filter built in my power amp. The second order I have no is too impactful to midbass, so I need to do for 2th order or perhaps for 4th and try to integrate it. Whatever it will be I think the passive line-level, no-capacitance filters in the power amp will be better than anything else with active stages.

Still, the I think the biggest problem is not the topology or implementation but the ambiguity of perception. Even myself, with my self-accused super-evolved listening intelligence, feel that I am kind of at last and do not know how to evaluate the quality of my ULF.
At sub 30Hz and high order filter there is no sound but rather the irrelevant tails of harmonics tails. To listen just them is not useful and they need to be heard only in context of rest of music. I have no problem to do it and I know what music to play and what to listen for. However, I am not sure if I have a clear picture what would be my “Imaginary Truth” in the ULF sound.

A few days ago an audio friend of my was experimenting with his new tweeter and told me how wonderfully his new tweeter reproduces metallic qualities of triangles and cymbals. I suggested that it was absolutely wrong criterion of judgment as metallic qualities of cymbals have no degrees of quality that our mind can acknowledge. It sound metallic but there are no shades of being metallic, not mention that in metallisism of cymbals is greatly depending by the recording techniques. In other worlds there is no cultural or musical reference upon the depth of being metallic.
The very same feeling, only on the opposite side of spectra I have about my ULF. Adding a bit presence of weight under 30Hz do a positive impact to sound but I am not sure that I can clearly feel a difference between good ULF and bad ULF, at least in my implementation. Sure if it were some kind of “openly bad ULF”, like posted sound or too much amplitude, then I get it. However, if the ULF does not do any particular bad things then the difference in bad ULF and good ULF is much more tolerable and to discriminate the thing is much more difficult.

It might be the case that all ULF that I getting in my room are bad ULF. Very possible and I more and more incline to feel this way. I never heard from playback, any playback, the ULF done in a way I want and like so I do not know what topology can deliver it. I have my vision how I would like ULF to be but I did not experience it in audio, so in a way I shoot blindly to a black Cat in a dark room. With all my clear vision how I would like my ULF to sound I have absolutely no association between this “perfect” imaginary sound of mine and the sound I am getting from my current ULF. So, I might get some “improvement” but it will not be the sound that I want.

Perhaps, Jessie is right about large woofers. Perhaps my small drivers arrays not used as arrays do smear the leading edge of the pressure front and give to me that “overly soft” ULF, overly saturated with second harmonics. I don’t know. To put my large woofers into the game and evaluate the ULF from them would require a construction of a large sealed box but I do not feel now to do it – I just have a few weeks none-dusty live and I like it. If someone from New England have a large sealed ULF section with resonance in 20s Hz and willing to demonstrate it to me then feel free to invite me. I would bring my power amp ….

The Cat

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